Analysis of the damage cause of VOD ladle lining refractories

Source: | Author:Changxing | Published time: 1759 days ago | 1267 Views | Share:

After repeated use of VOD lining, it was found that some of the slag line refractories were seriously denuded by thermal chemical and mechanical stresses. Corrosive silicate compounds have been shown to be harmful at high temperatures (upwards of 1750 ° c) and low pressures (1~200mbar).

(1) the slag by opening stomatal network penetration into magnesia chrome refractory, refractory in the silicate slag into low melting point for chemical reaction with the ternary compounds, such as low refractoriness C3MS2 (magnesium rhodonite) and CMS (calcium magnesium olivine), especially from the erosion of magnesium in magnesite chrome bricks in person to silicate phase. The common direct - bonded magnesia-Chrome bricks are unstable and partially replaced by "liquid - bonded" bricks, making such a system more susceptible to erosion by turbulent slag.

(2) Another wear mechanism of furnace lining is spalling. The magnesia-Chrome brick will break up with the rapid change of temperature after infiltration into slag. The most severely affected area is the transition zone between permeable and impermeable layers in the brick. This drastic temperature change causes the hot surface parallel to the brick to break.

(3) In addition, fe-containing mG-Cr refractories are affected by reduction oxidation expansion, thus accelerating material damage. The low PO2 system may result in the formation of metal inclusions during the vacuum deoxidation process of ladle metal refining. These inclusions consist mainly of metallic iron and small amounts of chromium (such as 90% atomic iron and 10% atomic chromium), which are produced by partially reducing chromium in bricks. The process is segmented reduction of MgO·Fe2O3, which is firstly reduced to mafic iron {(mg, Fe)O}, and then reduced to mafic iron containing a small amount of metallic iron. In the course of two smelts, the brick's REDOX reaction alternates (so called respiration) with a slight volume change that produces rupture and spalling. Therefore, it is certain that the production of magnesia tiles with high iron oxide content using South African chrome ore (low silica content, but higher iron oxide content than low iron oxide chrome ore produced in the Philippines) is extremely unfavorable.